Conventionally, plasma torches are comprised by a torch body with, in its rear portion, connections to fluid supply conduits, particularly of plasmagenic gas, an electric current, and in its front portion, means for mounting the electrode body and the nozzle.
In certain cases, so as particularly to facilitate maintenance and/or replacement of the worn or defective pieces, the torch can be provided with quick assembly/disassembly means, as described in the document EP-A-599709, which is incorporated herein by reference.
As set forth in detail hereafter, in conventional plasma torches, the electrode properly so called is generally carried by a support element, also called an electrode body, which performs moreover a radiator function by permitting the discharge of a portion of the heat given off during welding, cutting or plasma marking, by heat exchange with a cooling fluid.
Conventionally, the electrode body has the shape of a tapped sleeve of circular cross-section. The tapping provided on a portion of the internal peripheral surface of the sleeve permits ensuring securement by screwing of the electrode body onto the electrode carrier, which has a complementary screw thread on it external circumference.
However, it has been observed that with this type of mounting relying solely on securement by screwing, the centering of the electrode body is not always correctly ensured.
There accordingly results accelerated deterioration, particularly of the electrode properly so called and in particular of the nozzle, thereby giving rise to more frequent replacement of the assembly constituted by the electrode and the torch nozzle and correspondingly an increase of cost.
Moreover, if an increase in the length of the screw threading permits partially overcoming this problem of bad centering of the electrode, this solution cannot be considered as totally satisfactory because it involves a decrease of the internal surface permitting heat exchange between the cooling fluid and the electrode body and hence an important loss of cooling efficiency of this latter. In other words, the increase of the length of the securement screw threads takes place to the detriment of heat exchange, which is not acceptable.